From 3aeb2d1a514c708844cbc60aaa6f0c01eba96a00 Mon Sep 17 00:00:00 2001
From: Alex Menkov <amenkov@openjdk.org>
Date: Fri, 13 Mar 2020 12:25:25 -0700
Subject: [PATCH] 8217441: Failure of ::realloc() should be handled correctly
 in sawindbg.cpp

Reviewed-by: cjplummer, sspitsyn
---
 src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp b/src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp
index 8748dd163ce..e95dd065050 100644
--- a/src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp
+++ b/src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp
@@ -312,11 +312,13 @@ STDMETHODIMP SAOutputCallbacks::Output(THIS_
     }
     strcpy(m_msgBuffer, msg);
   } else {
-    m_msgBuffer = (char*) realloc(m_msgBuffer, len + strlen(m_msgBuffer));
-    if (m_msgBuffer == 0) {
+    char* newBuffer = (char*)realloc(m_msgBuffer, len + strlen(m_msgBuffer));
+    if (newBuffer == nullptr) {
+      // old m_msgBuffer buffer is still valid
       fprintf(stderr, "out of memory debugger output!\n");
       return S_FALSE;
     }
+    m_msgBuffer = newBuffer;
     strcat(m_msgBuffer, msg);
   }
   return S_OK;